/Engine/Source/Runtime/Core/Public/Internationalization/TextLocalizationManager.h
If an entry exists for the specified namespace and key, returns true and provides the localization resource identifier from which it was loaded. Otherwise, returns false.
bool GetLocResID ( const [FTextKey](API\Runtime\Core\Internationalization\FTextKey) & Namespace, const [FTextKey](API\Runtime\Core\Internationalization\FTextKey) & Key, [FString](API\Runtime\Core\Containers\FString) & OutLocResId ) const